1. Field of the Invention
This invention relates to an improved sailing system, and in particular to a construction and arrangement of a mainsail and its support rigging which results in a large increase in propulsive efficiency by reducing turbulence on the leeward side of the mainsail.
2. Description of the Prior Art
It has been well established, that, when a sailboat is either reaching or is beating to windward, (i.e. sailing generally into the wind) an important force acting on the boat is developed by the wind creating a partial vacuum or a pressure gradient on the leeward side of the sail. It has also been well established that a sail will be more efficient if the flow of air on the leeward side of the sail is relatively smooth and undisturbed as in laminar flow, than if the flow of air is turbulent. In a conventional sailing system, the mast causes considerable turbulence along the leeward side of the sail because it prevents a smooth entry of the wind to the leeward surface of the sail. Thus, the position of the mast with relation to the leading edge of the sail, relative to the wind direction, is extremely important in determining the character of flow on the leeward side of the sail, and therefore the efficiency of the sail.
As illustrated in FIG. 61 on page 96 of MARCHAJ, Sailing Theory and Practice, Dodd, Meade & Co., N.Y., 1964, and the accompanying text, an efficiency gain in the order of twenty-eight percent can be achieved if the mast is placed to windward of the leading edge of the sail on a round mast. This is illustrated on Model C of FIG. 61 of MARCHAJ. One way to achieve this, with a conventional mast, where the mainsail bolt rope is run up a groove in the after edge of the mast, would be to rotate the mast. For example, if the boat is on a port tack, the mast would be rotated counterclockwise (when looking down on the mast), thus wrapping the sail around the mast so that the forward edge of the sail leads from the leeward or starboard side of the mast. Conversely, if the boat is on a starboard tack, the mast would be rotated clockwise (when looking down on the mast), thus wrapping the sail around the mast so that the forward edge of the sail leads from the leeward or port side of the mast.
My sailing system comprises a rotating mast having at its top or masthead a masthead housing containing an antifriction bearing, a floating spreader having an antifriction bearing, and a mainsail having a slot permitting the sail to pass over the floating spreader when the sail is being wrapped around the mast.
Various embodiments of rotating masts have been used for many years. Presently, there are rotating masts on various multihull classes, both in the United States and in England as well as a number of racing dinghies. Some of these rotating masts are in use with conventional headsails. They do not, however, present the mast in a constant position of always being able to be on the windward side of the mainsail, and they do not have any spreaders that do not rotate with the mast. These rotating masts have rudimentary spreaders or struts that rotate with the mast and offer little support. A rotating mast gains little efficiency over conventional fixed masts because it does not solve the basic fault of the mast, viz. the sail produces turbulence on the leeward side of the mainsail or "bad air" on the leeward side of the mainsail. This "bad air", so to speak, is present because the shape of the mast disturbs the airflow on the back or leeward side of the sail. There have been through the years many attempts to change this "bad air" condition. For example, there is the Chinese lug sail, the modern rotating "wing" mast and attempts to support the mainsail independently of the mast. These innovations have had, only, partial success. The proof of this partial success is the lack of general acceptance by sailors.
My invention, by the use of "floating spreaders" that are not connected to the mast imparts the same efficiency to the main that was formerly possible only in headsails. Instead of "pushing" against the mast to prevent its deflection, the "floating spreader" is the part of the rigging that is put under strain and tension and "restrains" the mast as it attempts to bend out of shape. Of course, this line of action eliminates any and all through mast bolts or fastenings of any kind, making the mast much stronger for its shape and weight. The mast can, therefore, be made considerably smaller and lighter, thereby eliminating considerable weight and windage aloft, a desirable combination for increased speed under sail. This new development involves creating a sail which is reinforced where the slot in the sail clears the spreader. The mast, mounted on a turntable and held by the forestay and backstary attached to a housed bearing, can rotate 360.degree. at each change of tack when tacking or beam reaching.
An additional advantage to be gained by the subject invention is the possibility of sheeting the genoas much closer to the centerline because the spreader arms are relatively short, 36" wide on a 35' deck mounted mast, and are positioned on the foreward side of the mast. Also, sail abrasion by the spreaders is virtually eliminated. Because the mast can be made smaller and more streamlined in section, and because there are no fastenings between the base and the masthead, there exists a greater safety factor in rough weather sailing. The laminar flow of air on the leeward side of the mainsail has a profound effect on the efficiency of the jib or jenny. The sails can be flattened more and the slot narrowed so as to bring the jib or jenny closer to the masts, because it is no longer necessary to compensate for poor performance of the mainsail.
The addition of a second mainsail member held in the bolt rope slot introduces the world's first "soft sail" "wing mast". It is no longer necessary to reverse the mast on changing tack because the mast is positioned slot forward and is completely encompassed by the two sails.
If desired, a split boom arrangement can be installed for the cruising sailor and both sail members "wing out" for sailing downwind. This doubling of the mainsail area from the cockpit eliminates the necessity for headsails, viz. spinnaker, ballooner, staysail, etc. A foredeck crew to handle these difficult-to-set sails is no longer necessary. This arrangement would be ideal for the cruising sailor or one who is shorthanded.
Also, elimination of the turbulence on the leeward side of the mainsail has a beneficial influence on the drive and efficiency of the jib. With a "floating" spreader that has about 40% shorter arms than the conventional spreader and with the crossing foreshrouds, the jib can be sheeted in much closer in a tacking situation. Also, because of the absence of turbulence on the back of the mainsail, the wind in the slot areas is speeded up and there is less danger of backwinding the main, as would be the possibility with conventional rigging.
Because the mainsail is the most easily controlled sail aboard a sloop, the increased reliance with conventional systems, on the jib, genoa, staysail and spinnaker combination is very costly. The tall narrow rig (not, necessarily, devised for rotating purposes) involves a larger sail inventory, increased problems in staying the mast and additional demands on crew time and effort in setting, adjusting and maintaining the "headsail oriented attitude" on all points of sail. This has largely come about because these sails, supported on their respective forestays from the mainmast are free from the restrictions imposed by that mast, and are more efficient than the mainsail.
The acceptance of naval architects, designers and builders of the status quo in the mast, spreader and mainsail condition in its present form has resulted in more and more attention being paid to the development of headsail improvement. The modern sailing classes feature genoa sails with larger sail area than mainsails. The spinnaker has evolved where it is being used in all sailing courses except directly on the wind. This has resulted in the mast in the typical modern sloop rig being stayed further and further aft and resulting in the mainsail becoming smaller and less important in producing the power to drive the hull. The placement of the present-day mast and the reliance on the headsails detract from the importance of the mainsail and in moving the center of effort of the mainsail further aft profoundly affects the center of lateral resistance of the modern hull.
Once the loss in efficiency of the conventional mainsail is overcome and the mainsail becomes an efficient adjunct to the headsail drive, then there has been made a great improvement in the overall efficiency of the modern sailing boat of today. This is a main purpose of the subject invention.
Because the mainsail, in conjunction with the headsails, is, with my system, no longer at such disadvantage, and because the mainsail is so much more easily handled and controlled from the cockpit, it is possible that adoption of the subject system and its uses, especially among development racing classes, will profoundly affect hull design and sailing practice worldwide.
As the "floating spreader" eliminates the need for through fittings in the mast, the mast can be made smaller and lighter for racing and for curising rigs. Therefore, there is introduced a large safety factor.
Sailing systems and components thereof which can be found in the patent literature, and which should be considered when attempting to put my invention into proper perspective relative to the prior art, are shown by the following U.S. Pat: No. 92,577, granted July 13, 1869, to E. F. Burrows; No. 131,508, granted Sept. 24, 1872, to James H. David; No. 168,159, granted Sept. 28, 1875, to S. S. Jordan and J. C. Stevens; No. 383,594, granted May 29, 1888 to J. H. Rushton; No. 685,943, granted Nov. 5, 1901 to J. P. Pool; No. 3,149,603, granted Sept. 22, 1964 to Joseph DsainteClaire; No. 3,415,215, granted Dec. 10, 1968 to Oscar B. Plym; No. 3,487,800, granted Jan. 6, 1970 to Hoyle Schweitzer and James Drake; No. 3,610,190, granted Oct. 5, 1971 to Geoffrey C. Palmer; and No. 3,795,215, granted Mar. 5, 1974, to Frank W. Butler.
A sailing system as defined, herein, comprises the sails, mast, spreader, fittings, and all standing and running rigging on a sailboat, but not the sailboat itself. The description is concerned with the sailboat having a sloop-rig, that is, having a single mast, a triangular mainsail and a triangular jibsail or a genoa. However, it is to be recognized that my sailing system can be adapted for use with any marconi rig.